Locking system and torque limiter for an electrically actuated thrust reverser

ABSTRACT

A thrust reverser is described that comprises a new type of locking means for locking an actuator in position so that maintenance can be performed on the machine. The locking means comprises a removable locking device for preventing movement of an actuator. The locking means may also function in one configuration as an end cap. An actuator is also described comprising a removable torque limiting device for limiting torque of the actuator.

FOREIGN PRIORITY

This application claims priority to European Patent Application No.17275151.3 filed Sep. 28, 2017, the entire contents of which isincorporated herein by reference.

TECHNICAL FIELD

The examples described herein relate to electric thrust reversers suchas those used in aircraft. In particular, the examples described hereinrelate to means and methods for locking the actuators of and further tolimiting the torque of such electric thrust reversers.

BACKGROUND

Electric thrust reversers are utilized in aircraft to change thedirection of thrust of the aircraft engine, (i.e. so that the thrust isdirected forward, rather than backward) so as to decelerate theaircraft. These are used to slow the aircraft down upon landing.

Known system thrust reversers that are actuated electrically often use anumber of ballscrews operating in parallel from a motor. The actuatorsoperate collectively via a number of interconnecting shafts.Traditionally, during maintenance, the ballscrews are operated via amanual drive unit and with an intermediate locking device which ispermanently mounted within the transmission.

SUMMARY

An actuator for use in a thrust reverser is described herein, comprisinga removable locking device for preventing movement of said actuator. Theactuator comprises a drive spline for moving said actuator, said drivespline having a hollow shaft with an inner surface. The locking devicecomprises a first end and a second end with a shaft having an outersurface extending between said first and second ends. The inner surfaceof said hollow shaft of said drive spline is sized and shaped to receiveand mate with said outer surface of said shaft of said removable lockingdevice to thereby prevent movement of said thrust reverser and thereforealso said actuator when said shaft of said locking means is positionedwithin said hollow shaft of said spline.

In any of the examples described herein, the inner surface of said drivespline hollow shaft and said outer surface of said shaft of said lockingdevice may be correspondingly contoured to provide a matching interfacebetween the two shafts.

In any of the examples described herein, the inner surface of said drivespline hollow shaft and said outer surface of said shaft of said lockingdevice may comprise correspondingly shaped and sized elongated ridges.

In any of the examples described herein, said removable locking devicemay have a greater diameter D1 at said second end than a diameter D2 atsaid first end. The second end may act to seal the entrance to saidhollow shaft of said drive spline when said second end is positionedover the entrance to said hollow shaft and when said shaft of saidlocking device is not positioned within said hollow shaft.

In some examples, the end cap and the locking means are reversible inthat in a first configuration, the first end of the locking means may beused to lock the actuator, and in a second configuration, the opposite,second end of the locking means comprises an end cap.

In some examples, the locking means does not comprise an end cap at itsopposite end.

In some examples, the end cap does not comprise a locking means at itsopposite end.

An actuator for use in a thrust reverser is also described thatcomprises a removable torque limiting device for limiting torque to saidactuator and therefore also limiting torque to the actuator. Theactuator comprises a drive spline for moving said actuator, having ahollow shaft with an inner surface; and said torque limiting devicehaving a shaft extending therefrom, said shaft having an outer surface;and wherein said hollow shaft of said drive spline is sized and shapedto receive and mate with said shaft of said removable torque limitingdevice to thereby limit torque of said actuator.

In any of the examples described herein, said inner surface of saiddrive spline hollow shaft and said outer surface of said shaft of saidtorque limiting device may be correspondingly contoured to provide amatching interface between the two shafts.

In any of the examples described herein, the inner surface of said drivespline hollow shaft and said outer surface of said shaft of said torquelimiting device may comprise correspondingly shaped and sized elongatedridges.

A method for locking and preventing movement of an actuator that may beconnected to a thrust reverser is also described herein. The actuatorcomprises a drive spline for moving said actuator, said drive splinehaving a hollow shaft with an inner surface; and said method comprisingthe steps of: providing a removable locking device, said locking devicecomprising a first end and a second end with a shaft having an outersurface extending between said first and second ends, and inserting saidshaft at said first end of the device into said hollow shaft of saiddrive spline; said hollow shaft being sized and shaped to receive andmate with said shaft of said removable locking device to thereby preventmovement of said actuator.

A method for limiting torque of an actuator in a thrust reverser is alsodescribed herein, said actuator comprising a drive spline for movingsaid actuator, said drive spline having a hollow shaft with an innersurface; and said method comprising the steps of: providing a removabletorque limiting device comprising a shaft extending therefrom, saidshaft having an outer surface, and the method further comprising thestep of inserting said shaft at said torque limiting device into saidhollow shaft of said drive spline; said hollow shaft being sized andshaped to receive and mate with said shaft of said torque limitingdevice to thereby limit torque of said actuator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a known example of half of a single nacelle that may beused in an aircraft.

FIG. 2 depicts a new type of thrust reverser and new means of lockingthe thrust reverser as well as limiting the torque of the thrustreverser

FIG. 3 depicts the thrust reverser of FIG. 2 wherein the thrust reverserand therefore actuator is locked

FIG. 4 depicts the thrust reverser of FIGS. 2 and/or 3 wherein a torquelimiter is applied to the thrust reverser.

FIG. 5 depicts the internal workings of a known manual drive unit as maybe used with the example shown in FIG. 1.

DETAILED DESCRIPTION

FIG. 1 depicts half of a single nacelle, as is known in the art and thatmay be used in an aircraft. The nacelle contains an electricallyactuated thrust reverser that comprises first 11 and second 12actuators. The thrust reverser also comprises a motor 13 which mayfurther comprise a power off brake 13′. This power off brake may beeither manually or electrically released. The motor 13 is connected viaa first flexible drive shaft 14 to a dual gear set 15. The dual gear set15 further comprises means for locking the thrust reverser mid-stroke.This is a requirement when the aircraft is undergoing maintenance, forsafety reasons. Usually, the means for locking the thrust reversercomprises a pin (not shown) which physically prevents the gears in thedual gear set 15 from moving. The drive gear set 15 may further comprisea manual drive unit 17 which acts as a torque limiting device.

The internal workings of a known manual drive unit 17 with a mid-strokelever lock are more clearly shown in FIG. 5. The manual drive unit 17may comprise a rotary cam 400 which is indirectly connected to springloaded pistons 410. In use, movement of the cam 400 allows the twospring loaded pistons 410 (only one shown) to lift into slots within theshaft of the piston 410. Although the piston 410 is permanently gearedto the TRAS transmission, this stops movement of the transmission andlocks the thrust reverser and thereby also the actuators in place andprevents them from moving.

A second flexible drive shaft 14′ connects the dual gear set 15 to thedrive spline(s) 11′ of a first actuator 11, and a third flexible driveshaft 14″ connects the dual gear set 15 to the drive spline(s) 12′ of asecond actuator 12. These flexible drive shafts 14, 14′, 14″ allowrotation of the drive shafts and further enable the shafts to beflexibly installed within the nacelle and relative to the othercomponents of the thrust reverser 100. Further components as are knownin the art may further be present, such as means for providing positionfeedback 18, e.g. a rotary variable differential transformer (RVDT).

The manual drive unit 17 and intermediate locking device 16 aretherefore permanently mounted within the transmission of this knownsystem. Unfortunately, however, this results in disadvantages since itleads to a greater mass, increased cost as well as an increase in systeminertia.

The examples described herein and below, with reference to FIGS. 2 to 3therefore aim to overcome such disadvantages with known devices.

In particular, the examples of improved thrust reversers describedherein use a simplified means of providing both a torquelimiting/controlling function as well as a locking functionality, whichin turn results in the same functionality as known devices, but whichare cheaper, lighter and provide no increase in inertia to the system.

An example of an improved thrust reverser 200 and means for locking 216a thrust reverser 200 is shown in FIG. 2. In this figure, the samereference numerals have been used to represent the same features asshown in FIG. 1. This example differs from that shown in FIG. 1,however, in that the means 216 for locking the thrust reverser 200 inthis example is not permanently mounted within the transmission and themanual drive unit 217 of this example is also not permanently mounted inthe transmission.

As can be seen in FIG. 2, the motor 13, (which in some examples maycontain a power off brake 13′ which may be either manually orelectrically released) may be connected via a first flexible drive shaft14 to a drive spline(s) 11′ of a first actuator 11. A second flexibledrive shaft 14′ may then connect the first actuator 11 to the secondactuator 12.

In some examples, the new thrust reverser 200 may also contain furtherfeatures that are often found in such devices, such as RVDTs 18 etc.

This new example of an electrically actuated thrust reverser 200 mayfurther comprise means for locking 216 the actuators 11, 12, to preventmovement of the actuators 11, 12 during maintenance, as described above.In some examples this means for locking 216 may further be reversibleand additionally act as an end cap that fits over the drive spline 11′of the thrust reverser 200 in one configuration such as that shown inFIG. 2.

In the example shown in FIGS. 2 and 3, the means for locking 216 maycomprise a component having a first end 220 and an opposite second end230 with a shaft 240 extending there between. The locking means/end cap216 may be reversible in that, when positioned in a first configurationsuch as that shown in FIG. 2, the end or surface 220 that is in contactwith the drive spline 11′ is shaped and sized to match/mirror the shapeof the drive spline 11′ of the thrust reverser 200 over which it ispositioned, to sufficiently cover the drive spline 11′ so that thelocking means/end cap 216 acts as a cover to protect the drive spline11′ from environmental factors. This is depicted in FIG. 2, wherein thelocking means 216 is not activated and is merely being used as an endcap.

As can be seen in FIG. 3, when the thrust reverser 200 needs to belocked, e.g. when the device is undergoing maintenance, the user wouldremove the end cap/locking means 216 from its position relative to thedrive spline 11′ as shown in FIG. 2 and would use the opposite end 230of the locking means 216 in a second configuration, to engage with thedrive spline 11′ of the thrust reverser 200 to thereby lock movement ofthe spline 11′ and therefore the actuator 11 connected to the spline11′.

As can be seen in FIG. 3, the end 220 of the locking means 216 that actsas an end cap may in some examples therefore have a greater diameter D1than the diameter D2 of the opposite end 230 which causes locking. Thismeans that when used as an end cap, the drive spline is well covered,but when used as a locking means 216, the shaft 240 of the locking means216 can be inserted into the drive spline 11′ to thereby engage with andlock the spline 11′ in place.

In greater detail, the drive spline 11′ may be described as having ahollow shaft 211 that provides a female drive form whereas the shaft 240of the locking means 216 provides a male shaft 240 that has acorrespondingly shaped and sized outer surface. In some examples, theinternal surface 212 of the of the hollow shaft 211 of the drive spline11′ may have a unique surface contour and shape that provides a bespokeinterface that matches and mates with a correspondingly contoured andshaped outer surface of the shaft 240 of the locking means 216. Thebespoke interface between these correspondingly contoured surfaces (i.e.the inner surface 212 of the spline 11′ and the outer surface 241 of theshaft 240 of the locking means 216) are thereby able to lock thetransmission and prevent movement.

Although in the examples shown in FIGS. 2 and 3 the locking means/endcap 216 is reversible to provide both functions of end cap and lockingmeans, in some examples, these may be separate and distinct components.

In any of the examples described herein, the improved thrust reverser200 may further comprise a manual drive 217. This is depicted in use inFIG. 4. The manual drive unit 217 also acts as a torquelimiter/controller. In use, the end cap 216 as shown in FIG. 2 is firstremoved from the entrance to the hollow shaft 211 of the spline 11′. Themanual drive unit (and torque limiter/controller) 217 may also have amale section 280 comprising a shaft which has an outer surface that isalso contoured and shaped so as to correspond to the contour and shapeof the inner surface 212 of the spline 11′. This shaft 280 is thereforeinserted into the hollow shaft 211 of the spline 11′ as shown in FIG. 4and acts as a torque limiter/controller. This may further be manuallyadjusted.

As is described above, in these examples either or both of the manualdrive unit 217 and the locking means 216 are removable. They may alsocomprise a uniquely contoured and/or shaped outer surface that acts as abespoke interface with the inner surface 212 of the spline 11′ intowhich they are received. In some examples, the outer surface of theshafts 240, 280 of the locking means 216 and/or manual drive unit 217may have longitudinally extending ridges, similar to those found on atraditional “lemon squeezer” device.

It has been found that providing improved thrust reversers 200 such asthose described above with reference to FIGS. 2 to 4 results in a weightsaving of approximately 1.2% and with a thrust reverser actuator system(TRAS) cost saving of approximately 2.5%.

1. An actuator and a removable locking device for preventing movement ofsaid actuator, said actuator comprising a drive spline for moving saidactuator, said drive spline having a hollow shaft with an inner surface;and said locking device comprising a first end and a second end with ashaft having an outer surface extending between said first and secondends: wherein said inner surface of said hollow shaft of said drivespline is sized and shaped to receive and mate with said outer surfaceof said shaft of said removable locking device to thereby preventmovement of said actuator when said shaft of said locking means ispositioned within said hollow shaft of said spline.
 2. The actuator andremovable locking device of claim 1, wherein said inner surface of saiddrive spline hollow shaft and said outer surface of said shaft of saidlocking device are correspondingly contoured to provide a matchinginterface between the two shafts.
 3. The actuator and removable lockingdevice of claim 1, wherein said inner surface of said drive splinehollow shaft and said outer surface of said shaft of said locking devicecomprise correspondingly shaped and sized elongated ridges.
 4. Theactuator and removable locking device of claim 1 wherein said removablelocking device has a greater diameter D1 at said second end than adiameter D2 at said first end; and wherein said second end seals theentrance to said hollow shaft of said drive spline when said second endis positioned over the entrance to said hollow shaft and when said shaftof said locking device is not positioned within said hollow shaft.
 5. Anassembly including: an actuator having a drive spline for moving saidactuator, said drive spline having a hollow shaft with an inner surface;and a removable torque limiting device for limiting torque to saidactuator, said torque limiting device having a shaft extendingtherefrom, said shaft having an outer surface; wherein said hollow shaftof said drive spline is sized and shaped to receive and mate with saidshaft of said removable torque limiting device to thereby limit torqueof said actuator.
 6. The assembly of claim 5, wherein said inner surfaceof said drive spline hollow shaft and said outer surface of said shaftof said torque limiting device are correspondingly contoured to providea matching interface between the two shafts.
 7. The assembly of claim 5,wherein said inner surface of said drive spline hollow shaft and saidouter surface of said shaft of said torque limiting device comprisecorrespondingly shaped and sized elongated ridges.
 8. A method forlocking and preventing movement of an actuator, said actuator comprisinga drive spline for moving said actuator said drive spline having ahollow shaft with an inner surface, said method comprising: providing aremovable locking device said locking device comprising a first end anda second end with a shaft having an outer surface extending between saidfirst and second ends; and inserting said shaft at said first end of thedevice into said hollow shaft of said drive spline; said hollow shaftbeing sized and shaped to receive and mate with said shaft of saidremovable locking device to thereby prevent movement of said actuator.9. A method for limiting torque of an actuator, said actuator comprisinga drive spline for moving said actuator said drive spline having ahollow shaft with an inner surface, said method comprising providing aremovable torque limiting device comprising a shaft extending therefrom,said shaft having an outer surface; inserting said shaft at said torquelimiting device into said hollow shaft of said drive spline; whereinsaid hollow shaft is sized and shaped to receive and mate with saidshaft of said torque limiting device to thereby limit torque of saidactuator.